Time and temperature dependent multiple hierarchical NiCo₂O₄ for high-performance supercapacitors

Abstract

A multiple hierarchical NiCo2O4 (denoted as P-100), which was constructed of nanosheets covered with nanowires, was obtained by a facial hydrothermal method in combination with annealing treatment at 300 °C. The hydrothermal temperature and reaction time play key roles in the formation of the unique hierarchical NiCo2O4 based on the morphology evolution. As a supercapacitor electrode material, the obtained P-100 displays a high specific capacitance of 1393 F g(-1) at 0.5 A g(-1). Furthermore, the assembled P-100//AC asymmetric supercapacitor demonstrates a high energy density (21.4 Wh kg(-1)) at a power density of 350 W kg(-1) and remarkable cycling stability. The good electrochemical performances of the P-100 are mainly due to its three dimensional hierarchical porous nanostructure and high specific surface area as well as the synergetic effect of the nanosheets and nanowires in NiCo2O4. The experimental results demonstrated that the multiple hierarchical NiCo2O4 is a promising electrode material for high-performance supercapacitors.